Telephone system



Jan. 28, 1930.

A. J. RAY 1,745,038 TELEPHONE SYSTEM Filed Sept. 29, 1927 8 Sheets-Sheet1 QR S T5 SK PCR TCR FL RS RIK RH 63 TIUETL D1" Hfihur l Jan. 28, 1930.A, 'J RAY 1,745,038 I TELEPHONE SYSTEM Filed Sept. 29. 1927 8Sheets-Sheet 2-.

Jan. 28, 1930. J, RAY 1,745,038

TELEPHONE SYSTEM Filed Se pt. 29. 1927 8 Sheets-Sheet 3 13 1 mm J. E: %fi Jan. 28, 1930. A, J, R-Ay U 1,745,038

TELEPHONE SYSTEM Filed Sept. 29. 1927 8 Sheets-Sheet 4 Jan. 28, 1930.

A. J. RAY

TELEPHONE SYSTEM Filed Sept. 29.. 1927 8-Sheets-Sheet 5 Jan. 28, 1930.RAY 1,745,038

TELEPHONE SYSTEM,

Filed Sept. 29, 1927 s Sheets-Sheei 6 Imren u Jan. 28, 1930. A- J RAY1,745,038

TELEPHONE sYsTsm Filed Sept. 29, 192'? s Sheets-Sheet 7 Jan.- 28, 1930.A. J. RAY I 1,745,038

TELEPHONE SYSTEM Filed Sept. 29, 1927 8 Sheets-Sheet 8 Patented Jan. 28,1930 neural) STATES PATENT O ARTHUR J. RAY, or oirrc' eo, ILLINOIS,ssisnon roAssocrArn-n TELEP ONE Ann 7 TELEGRAPH COMPANY, or KANSAS CITY,MISSOURI, A conrgonArzoiv or DELAWARE TELErHonn I SYSTEM Applicationfiled September 29, 1927,1'Sria1 No. 222,741, and in. Great BritainOctober 14, 1926.

The. present invention relates to telephone systems and is moreparticularly concerned with what is known as routine testing appara tus,that is to say apparatus arranged to re produce automatically the actualconditions of use for each unit in turn of a large group of similarpieces of apparatus. The invention a'lsois intendedto be applied moreparticularly to the testing of apparatus which can 10 only be testedwhile it is not actually in use and must not be busied to its normalmeans of access in order that a test may take place. It is generallyrecognized nowadays that routinetesting is'desirable, it" not essential,

particularly for complicated apparatus, 111

be tested. Thisclearly presents a difficulty in order that it may bepossible to anticipate faults rather than correct them after they occur,and for the test to be effective itis essential that every pieceofapparatus'shall the above-mentioned circumstances, and it is the mainobject of the ln'ventlon to deal with cases'ot this sort in a s mplemanner.

According to one feature" ofthe invention in V an automatictestingarrangement havinga 0 piece of apparatus is adapted to beprevented I hunting switch for associating with the test.-

ing equipment the various pieces of apparatus to be tested, idlepiec'esof apparatus are tested in turn until all have been dealt with and afrom seizure by the hunting switch inconsequence of a special potentialassociated there with due to the completion of the test;

A further feature of the inventionis the 5 provision of an automatictesting arrangement for the routine testing oftelephone apparatus whenSuch apparatus isnotin use in which means associated with the testlngequipment enable part cular pieces of appara in use So that certaintests may be carried out in conjunctionwith the user ofthe apparatus,

" stood from the following description of one method of carrying theinvention into effect which should be taken in conjunction with theaccompanying drawings. Clearly any routining arrangement will need tobe'specially de signedin view of the apparatus it is desired tu s to beassociated withsaid equipment when I to test and the arrangement shownhas been over an order wire are setup on asingle set of digit keystheoperation of which serve to control an impulse sender to send out thenecessary trains of impulses for operating automatic switch-es toconnect with the wanted line. As a general rule the B operator will haveL0 trunks incoming to her position, though in particular cases thisnumber may be increased to 50. Moreovenin view of the fact that thecomplete operation of an impulse sender takes several times aslong astheset, ting of the digit keys, it is arranged that as i many as" fourimpulse senders; can be associated withher positlon at a time in orderthat she may workcontinually at full speed,

the impulse senders being accessible in com-1 I mon to a considerablenumber'of operators.

The testing of the complete apparatus falls naturally into two parts,one comprisingthe testing of the actual impulse senders which may bedone as described'in British Patent No. 267,606 and the other thetesting of the junction relay sets and apparatus for associating impulsesenders with the operators keyset. A-little consideration will Show thatfor a complete test to be carried out it is necessary v to employ theapparatus at the operators position used for associating an idle impulsesender with that posltiomhence it follows that the test cannot becarried out while the position is in service.

Referring now to the drawings comprising Figs, 1-8 ;F1g's. 1 and 2 Showthe various con trolling keys and a number of the associated relays;Figs. 3 and tshow a further group of the relays controlling thero'utiner; Figs. 5 and 6 show the test switch TS, the ro'utine'in- Idicating switch R18 and the number-set-up switch NS, together with thefault indicating lamps for indicating the progress of aparticular test;while Figs] and 8 Show the distribution equipmentvbymeans of whichconnect-ion is made with each position in turn, and also with each1unct1on in turn at a'par ticular position. In order to facilitate theunderstanding of the circuit, the description will be divided into twoparts, firstly consideration of the arrangements by which connection ismade in turn to the various positions and each junction at the positionis tested, and secondly consideration of the actual tests which arecarried out on the junction and the circuit arrangements by means ofwhich they are applied.

Considering first, therefore, the distribution equipment in thearrangement shown, it is assumed that the test set is to serve for 60operators positions and that each position has 50 incoming junctions andmeans for associating four impulse senders with the position at a time.The position distribution equipment comprises a primary distributor PDfrom which access is had to three secondary distributors SD SD of whichonly SD and SD are shown since the circuits of SD are similar.Preferably the contacts of the primary distributor PD are multipledround the bank as shown in Fig. 7, so as to avoid unnecessary operationof the switch. Since it is not found possible to provide the secondarydistributors with sufficient wipers for all the functions which they arerequired to perform, each one has associated with it an auxiliarysecondary distributor of which only the auxiliary secondary distributorASD associated with the switch SD is shown in Fig. 8. Each secondarydistributor is wired to have access to 20 operators positions and whenall .the 20 have been tested or found busy, the

primary distributor is advanced so as to connect up the succeedingsecondary distributor. Associated with each position are a pair ofjunction distributors such as JD and JD .shown in Fig. 8, which aregiven access to a maximum of 24 and 22 junctions respectively. \Vherethe full 50 junctions are equipped, access is obtained to the last fourover the first four contacts of the distributor JD a suitable switchingoperation being performed to connect these junctions up in place ofjunctions 14 as will be described subsequently. The junctiondistributors are provided with a normal position in which the contactsare left dead and by this means the wipers of the junction distributorsassociated with all the positions may be inultipled together to theroutine test set and the position distributors ensure that the junctondistributors of only one position shall be operated at a time. It shouldbe mentioned with reference to Fig. 7 that the banks of wipers 618-620of the secondary distributor SD are wired to the various junctiondistributors in the same manner as is indicated by the wiring of thefirst contacts in the banks of SD. The bank of Wiper 617 is wired to thecontacts of the associated position battery feed relays wh le that ofwiper 621 is wired to the bank of the associated auxiliary secondarydistributor completed for changing over from junctions 1-4 to junctions4;" 50 where this is necessary. The other auxiliary secondarydistributors are wired in a similar manner. The bank of wiper 625 of theunction distributor J D is wired to the lamp leads of the variousjunctions, that of wi er 626 to the respective assignment leads an thoseof wipers 627 and 628 to the negative and positive trunk conductorsrespectively.

The operations involved in making a test will now be considered indetail. In order to set the routiner in operation, the attendantoperates the start key SK whereupon a circuit is completed for relay115. Relay 115 upon operating, at armature 116 prepares a circuit forthe test relay 131, at armature 117 completes a circuit for the relay119 and at armature 118 prepares the pulsing circuit to the firstsecondary distributor. Further, at armature 122 relay 115 completes acircuit for relay 127 which extends as follows: battery, winding ofmagnet 507 of the switch TS, lead 439, armature 313 and its backcontact, lead 726, lead 441, interrupter contacts 508, wiper 506 and itsnormal contact, lead 93, winding of relay 127, armature 122 and itsfront contact. Relay 119 now operates and at armature 120 opens thecircuit of relay 280 which is normally energized in the followingcircuit: battery, relay 280, lead 698, lead 407, normal contact andwiper 622 of the switch SD normal contact and wiper of the switch SDrepresented by the link 624, normal contact and wiper 616 of the switchSD lead 18, lead 664, armature 120 and its back contact to earth and atthe front contact of armature 120 extends earth over lead 686, lead 26,wiper 603 of the primary distributor PD, lead 23, winding of relay 215to battery so that relay 215 is operated and prepares circuits for thejunction distributors and auxiliary secondary distributor and also forthe relay 185. Furthermore at armature 121 relay 119 prepares a circuitfor stepping the junction distributors. At armature 129 relay 127prepares circuits for relays 152' and 180 and at armature 130 closes thepulsing circuit of the secondary distributor. Relay 119 moreover atarmature 123 opens the homing circuit of the primary distributor andprovides a locking earth, at armature 124 prepares a circuit forstepping the primary distributor after each secondary distributor hasrotated over all positions connected to it, at

armature 126 opens an alarm circuit over lead 57 V and at armature 12 5*co'nnects earth to motor start lead '94 and opensj'the normally closedcircuitf r relay 27 8' which extends as follows: battery, windingof'relay 278, lead 714,"l'ead 493, lead 845,'link 649 representingwipers and norlnalicontacts of all the junc tion distributors not shown,normal contact and wiper 637, norinal contact and wiper 630, lead 1,lead 665,back contact and armature toearth. Relay'278 now de-energizesthereby altering certain supervisory circuits as will be describedsubsequently. The

pulsing circuit completed on the operation of relay 127 extends fromearth, winding of relay 264, armature 267 and its back contact,

lead 47, armature 148 and 'its back contact,

lead 61, back contact and armature 286, lead 62, armature 13 6 and itsback contact, arrnature 118 and its front contact, front contact andarmature 130, armature 153 and its back contact, armature 167 and itsback contact,

lead 666, lead 27, wiper 605 or" the primary distributor and the firstcontact in its bank,

winding of magnet 610 of the secondary discircuit for theslow-to-pull-up relay 266 which upon operating in due course,r,atarniature 267 opens the circuit originally traced, whereuponrelay 264and magnet 610 fall back and the latter advances thE'SWltCll SD onestep. Relay 264 upon releasing, opens the circuit of relay 268 and thisin turn brings down relay 266 whereupon unless the opera-v .1

tors position then connected with is in con dition to be tested, magnet610 is again energized and the cycle recommences. Therelay 533 in Fig.16 is used for feeding battery to v the operators headset and when theoperator is absent from the position and has therefore withdrawn herheadset plug, relay 533 is deenergized and extends earthover armature534 and lead 408 to the first contact in the bank of the secondarydistributor Sl over which access is obtained to this position. It

will be understood that the battery feed relays ot' the other'operatorspositions are connected up similarly to other contacts in the banksoiithe' switches SD SD The secondary distributor continues to advancestep by-step owing to the pulses received from relays 264, 266 and 268until wiper 611 encounters a contact to which earth is'connected owingto the operatorjbeing absent from the corresponding position.Thereuponthe follo'wingcircuit is completed: earth connected to thiscontact over the back contact and armature of the battery feed-relaywiper 611, first contact in the bank of wiper 601 and saidiwiper, lead24, lead 691, lead 59, arinature 289'and its back contact, lead 60, backcontact and armature 160, back contactand armature "145, armature 116and -;its front contact, winding of relay 131, resistance'276 tobattery. Relay 131 is operated in this circuit and at armature133'prepares a circuit for the magnet 631 of the unction distributor J Dat armature 134 completes a c'ircuit'tor relay 152, at armature 135closes another-:

point in the cirouitofrelay and at armature 136 disconnects the pulsingearth from the magnet ofthe secondary distributor SD? and extends it tothe'magnet of the auxiliary secondary distributor ASD over lead 676,front contact armature 218, armature 191 and its back contact, lead 2,magnet 647, lead 840, lead 29 to battery through relay 233. Consequentlythe auxiliary secondary distributor now commences to step and this continues until relay is energized when'the auxiliary secondary distributorreaches the same position as its associated secondary distributor. Thecircuit for relay 185 may be traced from earth, wiper 604 and its firstcontact, wiper 615, multipling to wiper 646, lead 3, armature 219, andits front-contact, windr of relay 185-to-battery, andthe operation ofthe relay opens the stepping circuit at' armature 191. When relay 152operates, at

armature 153 it opens another point in the pulsing circuititothe-secondary distributor,

' at armature 155i completes a locking circuit fo'rfitself whichextends" as follows: battery, winding "ofrelay 152, armature 155 and its1 front contact, normally closed right-hand springs'of the re-start keyRS,ar1nature 169 and its baokcontact, front contact and arma- I ture 123.to, earth, at armature 156 opens a. point inthe circuits of the relays137, 143 and 162,'an'd at armature 157 prepares a circuit for'horningthe unction distributors. -T he operation of relay 185 also atarinatures186- 189 and 192 and 193 prepares the connection lli) ofthedi'git'andorder wire leads overleads 79'82 and 9 and 10'to' thewipers of the auxiliary secondary distributor, and atarrnature completesa circuit for relay 180'eX- tending as follows: battery,-winding ofrelay 180, front, contact and armature .190, lead 67 1,-front"contactand armature 135, armature 129 and its front-contact, front contactandarm'ature 134, armature-169 and its back contac't,:tront contact andarmature 123 to earth. -Relay 180 upon operating,at arrria- T ture181completes a circuit for relay 229 and Ithisflocks 'up'by way of armature230, at i armature 182 completesthe following circuit 5 for relay 330;battery, winding ofrelay 330,

lead 45, lead 683, armature 182 and itsfront" contact, lead 682,1ead 33,wiper 502 of the switch'TS andthe first contact in its bank,

lead 453 and-by-way of interrupter 485 to earth. Moreover at armature183 earth is connected over leads 679 and 44, armature 331 and its backcontact, lead 725, upper winding of supervisory relay 314 to battery,and at armature 184 the homing circuit of the test switch TS is Openedand earth is connected to wipers 501 and 503. Vhen the contacts ofinterrupter 485 next close, relay 330 is operated and at armature 331opens the circuit of the relay 314, at armature 332 completes a directcircuit for magnet 507 and at armature 333 completes a locking circuitfor itself extending as follows: earth, armature 332 and its frontcontact, lead 441, inter rupter contacts 508, lead 429, armature 333 andits front contact, winding of relay 330 to battery. The connection ofearth to wiper 501 completes a circuit for the first supervisory lamp542 over lead 753, which lights to indicate that a free position hasbeen found. Vhen magnet 507 has operated fully and opened interruptercontacts 508, relay 330 de-energizes thereby opening the circuit ofmagnet 507 so that the switch TS is advanced one step. The earthconnected to wiper 503 is now extended over lead 440, lead 35, backcontact and armature 163, armature 121 and its front contact, frontcontact and armature 133, lead 667. armature 176 and its back contact,armature 216 and its front contact, lead 20, wiper 613 and the firstcontact in its bank, lead 806, magnet 631 of the junc tion distributorJD lead 402, winding of supervisory relay 295 to battery so that magnet631 is operated. The succeeding pulse from interrupter 485 againoperates relay 330 and this in turn effects the advance of the testswitch. Vhen the test switch takes its next step and advances to itsthird position, the circuit just traced is opened and accordingly thewipers of the junction distributor JD are advanced one step. In case theposition which has been connected with should only just have beenvacated by the operator so that there is a call still in progress overthe first junction, there will be earth on the lamp lead and this willaccordingly be extended over the appropriate contact in the bank ofwiper 625, lead 13, lead 74, lead 720, armature 340 and its backcontact, lead 721, upper winding of relay 376 to battery. Moreover owingto the advance of the test switch, the initial circuit over lead 440 isopened and relay 334 is operated over wiper 503 and lead 443.Accordingly the following circuit is now completed: earth. relay 264,armature 267 and its back contact, lead 711, armature 379 and its frontcontact, lead 710, armature 335 and its front contact, lead 35 andthence over the circuit previously traced to the magnet of the junctiondistributor JD Consequently this switch is again operated and if one ormore further busy junctions are encountered, relay 376 remains operatedso that the movement continues until the switch J D has been moved intoengagement with a j unction over which no call is in progress. Relay 376will then de-energize and complete a circuit for advancing the testswitch which now continues its operation and applies the various testsin turn to this junction as will be fully described subsequently.

\Vhen wiper 503 has made a complete revolution and again comes intoengagement with the second contact in its bank, the circuit traced aboveagain becomes operative for advancing the junction distributor, and inthe ordinary course this will take only one step and the next junctionwill then be connected up for testing purposes. In case, however, thisjunction should still be in use or should be out of service for anyreason, there will be earth on the lamp lead and this will operate relay376 to step the junction distributor on past this junction as abovedescribed.

As already pointed out, the switch JD is arranged to deal with 24junctions, and when its wipers are advanced into engagement with thelast of these junctions, the following circuit is completed: earth,wiper 629 and the 24th contact in its bank, lead 12, winding of relay172 to battery. Relay 172 upon operating, at armature 173 shuntsarmature 176 and its back contact and at armature 174 completes acircuit for relay 175. The latter upon operating, at armature 178 locksto earth at armature 123, at armature 176 prepares a circuit for themagnet 638 of the junction distributor JD, and at armature 179 preparesan auxiliary circuit for the magnet of the junction distributor JD \Vhenthe testing of this junction has been completed and the test switchagain reaches position 2, earth is again connected to lead 440 and isextended to the magnets of both distributors JD and JD hence JD isadvanced to its 25th or normal contact and J D takes one step and teststhe first junction in its bank. \Vhen the switch J D steps, the circuitof relay 172 is opened and it thereupon releases and prevents anyfurther pulses being sent to magnet 631. If the first junction in thebank of JD is idle and in service the usual tests are carried outthereon and the switch JD is advanced one step to connect up asucceeding junction.

Vhen all the junctions accessible from the bank of the switch .11) havebeen tested, the switch wipers will be advanced to position 23 whereupona circuit is completed as follows: earth, wiper 636 and the 23rd contactin its bank, lead 11, lead 669, winding of relay 166 to battery. Relay166 upon operating, at armature 167 opens a point in the circuit forstepping the secondary distributor, at annature 169 opens the circuitof. relays 109, 152, 175 and 180, at armature 170 closes a point in thecircuit of relay 285 and at armature 171 completes a. circuit forstepping the junction distributor JD a further step. \Vhen relay 180de-energizes, earth is supplied at lead 805, first contact in the'bankof-w1per armature 184 for homingthe test switch and when this reachesnormal position, relay 127 is operated. Relay 175 being slow to releaseholds up for a moment and when'it de-energizes the wipers of the switchJD are advanced a further step and the circuit of relay 166 is thenopened and it a slowly releases.-

With the wipers of J D in the 24th position, I

the following circuit: iscompleted: earth; wiper 636and the 24th contactin its bank,

612 and said wiper, first contact in the bank ofwiper 602 and saidwiper,lead 25, lead- 673, armature 154 of relay 137,- and itsback; icontact to the lower terminal of the winding of relay 181. Since the,original earth connection to theother terminal of this winding is stillintact, relay 131 is now short-circuited and accordingly de energizes,thereupon at armature 136 again connecting up'thepulsing circuit fromrelay 264 for advancmg the sec:

ondary distributor. ,Accordingly conditions are now similar to thoseobtaining wh'enL-the test was started and the secondary distributor SDhunts to find an idle position. When such a. position is found asindicated by the presence ofearth on theassociated contact in the bankof wiper 611, relay 131 again oper-g ates and at armature 136 completesthe circuit for advancing the auxiliary secondary d1s-: tributorcorrespondingly. The appropriate on which tests are made asgbeiore. I

then be completed as. follows: earth, wiper 604 and the first contactinits banlt,-flwiper- 615fand the 21st contact in'rits bank,- lead 403,windingof relay 297 to battery. Upon the operation of relay 297 acircuit is completed.

from earth, armature 124 and its front contact, lead 689, lead 69,armature 298 andlts front contact, lead 168, winding rot-"magnet, 607 ofthe primary distributor, lead 29, wind-, ing of relay 233,150 battery asbefore. Mag n et 607 thereupon energizes but does not yetad-:Since'relay 131i is still not-operated a circuit is again com-- Vanceits associated; wipers.

pletedfor advancing the secondary distributor S13 and wiper 615accordinglyleavesits 21st contact. Consequently the CllOllliJgIfOI relay297 is now opened-and its,,relelases, thereby opening the circuitforqthemagnet,

- 607 of the primary} distributor whichj'ad vances the wipers one step.The-secondary distributor SD? is thus connected up and the positionsaccessible overitsbankjare then tested in the mannerpreviouslydescribed. When it arrives at position2l, a circuit iscompleted for advancing the primary dis-: tributor in the. same way asabovedescribed, nand accordingly the secondarydistributor to thefactthat it is heldopen' at armature 231, relay 229 being operated at thistime. Consequently the switch SD .continues to step in response topulses from relay 264 until it'engagesiits 23rd contact whereupon acircuitis zcompleted from earth 'on wiper 604 asbe fore, lead 401,winding of relay 292 tobattery. Relay 292 upon operating at armature"293 opens thelocking circuit of relay 229, thus causing it to releaseandiat armature 294 extends earth fromlead 69 over above circuit isopened. due tow the further stepping of the distributor SD It hasalreadybeen pointed out thatxthe tests on an operators position can onlybe made when the position'isnot in use andaccordinglyit will be clearthat even ifthe routine testing is undertaken at times of light loadaswould normally be the case, a single operationof the routinerwould beunlikely to test all the operators positions; It is unct1on distributoris then advanced one step: and if necessary hunts to find an idlejunctio r therefore provided in 'the presentinstance that afterallpositionshavebeen tested once for busy or 'idlecondition and'the idleones dulyflroutined, the various positions. are againitest'ed, only onthis occasion not only positions which are actually busy have to be 1passed over but also those which have been "routined on the previousoperation 'of the;

distributing switches. The necessary discrimination-is effected due tothe position.

which the second junction distributortakes up when a position has beencompletely routined; Reference to Figs??? and 8fwill" show that inthiscase earth is appliedover the 24th contact in thebank of wiper 636 ofthe junction distributor J 1) to thercontact associated with theposition in the bank of wiper 612' andfthis will-have; the 'effectfofproducing a short-circuit on relay'131, so that in the case ofpositionsac-tually in use no earth is supplied. to this. relay. and inthe case 7 i of positions which "areanotwin' use but which.

have already been tested earth is supplied to both terminals of therelay so that in either 7 event the relay --isunable to operate; Ac-

cordingly it does not openthepulsing circuit 7 i I to. the. secondarydistributor and this switch 1 stepsi overthepositionQ -It' willberecalled" that when a free position is encountered, relay 131 operatesandcompletesa'circuitfor I relay 180 andthis'in'turnoperates relay 229which locks up clependentupon relay 280fand 292: Hence if all thesecondary distributors shouldpass over the whole of their banks withoutfinding any'position in a condition to be tested, relays 131, 180 and229 will not be operated and in this case when wiper 621 of thesecondary distributor SD engages its 21st contact, earth is extendedover lead 15, armature 231 and its back contact, lead 685, lead 65,upper winding of relay 285 to battery. Relay 285 is a two-step relay andat this time only operates its light armature 290 therebyshort-eircuiting its lower winding by earth on the left-hand contacts ofthe restart key RS. Then the secondary distributor SD receives a furtherpulse, the initial energizing earth is removed and relay 285 thenoperates fully over both its windings in series and is accordinglylocked up to the re-start key BS. The operation of relay 285 at armature291 completes a circuit for the routine finished lamp 284 and the lowerwinding of relay 314 in series and relay 314 operates with results to bedescribed subsequently. Relay 285 moreover at armature 286 opens thenormal pulsing circuit for the secondary distributors and auxiliarysecondary distributors, at armature 288 opens an auxiliary energizingcircuit for itself, at armature 289 opens a point in the circuit ofrelay 131 and at armature 287 connects earth to wiper 616 of secondarydistributor SD This switch accordingly commences homing and when it hasreached its normal position the homing earth is extended to thesecondary distributor SD When this switch in turn has reached its normalposition the homing earth is transferred to the switch SD and when thisswitch has returned to normal a circuit is again completed over lead 407for relay 280. Relay 280 upon operating, at armature 281 opens a furtherpoint in the locking circuit of relay 229 and at armature 282 opens apoint in the magnet alarm circuit.

In case the attendant discovers by operating the key RIK that a numberof positions have still not been tested, he may leave the routiningapparatus in this condition for an interval and then by operating there-start key RS, again set it to hunt for and routine positions whichhave not yet been dealt with. When the re-sta-rt key is pressed, thelooking circuit for relay 285 is opened and it releases therebycompleting the pulsing circuit for the distributor SD. The operation nowproceeds as before and continues until all three distributors again makea complete rotation without finding any position in condition to betested. It will be noted that in these circumstances only the secondarydistributors are restored to normal but not the junction distributors,since these switches indicate by their off-normal position that theassociated position has already been tested.

When the start key is restored, on the completion of the test or at anyother time the circuit of relay 115 is opened and upon deenergizing itopens the circuit of relay 119. Upon the de-energization of relay 119, ahoming circuit for the secondary distributors is completed from earthover armature 120 and its back contact and leads 664 and 18 to wiper 616of the distributor SD whence it is extended in turn to distributors SDand SD Over armature 123 and its back contact earth is applied overleads 688 and 28 to the bank of wiper 606 so that this is effective inbringing about the homing motion of the primary distributor. The earthover the back contact of armature 125 is extended over leads-665 and 1to wiper 630 of the junction distributor J D and serves to efiect thehoming motion of this switch. When the switch reaches its normalposition, the homing earth is extended to the switch J D and this inturn is operated to normal. All the other unction distributorsaccessible to the routiner are homed in a. similar manner, one after theother, and accordingly all the apparatus is left in the position shownready for a further test to be initiated, for instance the next day. Thesole exception is the auxiliary secondary distributors for since theyalways follow their associated secondary distributors when they arerequired for use it is unnecessary to return them to a definite normalposition. It may be mentioned also that with the arrangement shown, theoperation of the key RS is necessary to bring down relay 285, but thiscould if desired be dependent on relay 115 so that it would release whenthe start key was restored.

Consideration may now be given to the actual tests which are made oneach junction. The initial circuit for stepping the test switch TS hasalready been traced, this being comp eted owing to the operation ofrelay 330 when relay 180 is energized. It was pointed out, moreover,that with the test switch engaging its second set of bank contacts. acircuit is completed over lead 440 for advancing the first junctiondistributor of the seized position one step, the test switch meanwhilemoving to engage its third set of contacts. In case the junction whichis then connected with should. have a call in progress or should be outof service, there will be earth on the lamp lead and accordingly thejunction distributor will again be advanced under the joint control ofrelays 334 and 376. \Vhen relay 376 deenergizes, a clrcuit is completedfor relay 330 extending as follows: battery, winding of relay 330, lead45, lead 683, armature 182 and its front contact,'lead 682, lead 33,wiper 502 and the third contact in its bank, lead 461. lead 736, backcontact and armature 382. lead 735, interrupter'485 to earth, so thatthe switch TS is moved to fourth position. In this position a circuit iscompleted over the fourth contact in the bank of wiper 503 and lead 446for relay 336. Upon the operation of relay 336, earth through the lowerwinding of relay 376 is connected over lead 7 24, front contact andarmature 340, lead 720, lead 74, lead 13 and over wiper 625 of theswitch J D to the lamp lead; if .this lead is continuous, batterythrough the lamp will be operative to energize relay 376. Moreover atarmature 337 earth is connected over lead 7 09 through the winding ofrelay 389 and over lead 405 and wiper 628 to the positive trunkconductor. In case this trunk should be in contact with any adjacentleads, a circuit will now be completed for re lay 389 and it willthereupon operate. Fur thermore at armatures 338 and 339 the wind ingsof relay 385 are connected together and over leads 718 and 404 and wiper627tothe negative trunk conductor. Thewindings of relay 385 areconnected in opposition s0 that if there is no potential on the negativeconductor at this time, the relay will not operatebut V in c-asethenegative line should be in contact with some adjacent leads, relay 385will be unbalanced and will therefore operate. .1 The.

condition for asuccessful test is therefore that relay 376 should beoperated but that relays 385 and 389 should not be operated. In thesecircumstances no circuit is completed for the fault indicating lamps 538540 which are wired to the fourth position of thetest switch;

It will be seen however that if relay 376 fails to come up, earth onlead 437 will be extended over backcontact and armature 378, lead 708,lead 438,1ead 748, lamp 538, to battery. Similarly if relay 385 operatesa circuit is com; pleted over frontcontact andfarmature 386 and leads706, 436 and 749 for lamp 539 and if relay 389 operates lamp 540 islighted over armature390, lead 705, lead 435 andlead 750. A circuit isnow completed from the interrupted generator 400 over lead 737,"frontcontact and armature 383, back contact and armature 387armature 391 and its back contact, lead 7 38, lead 462, fourth contactin the bank of wiper 502 and said wiper, lead 33, lead 682,

front contact and armature 182, lead 683. lead 45, winding of relay 330to battery. Relay wiper 503 and lead 447 for relay 341. Upon j theoperation of relay 341, battery through re-' sistance 399 is connectedat armature 342 over lead 709 through relay 389 to the positive trunkconductor anda'at armfature343 earth through the lower winding of relay,385 is connected over lead 719 to the negative trunk conductor. .Relay385 only operates if there is battery on the negative line, while the resistance of relay389 and resistance 399 in series is suflicientlyhighto' prevent the opera;

tion of two line relaysin parallel if two po's'itive lines should be incontact, but will allow one line relay to operate if there is nocontact. Relay 389 is also now operated'and;theconditions set up by thistest are equivalent to the" taking of the junctionbyan A operator beforeit has been assigned. Accordingly if tact and lead 721 to the upperwinding of relay 376. Each time relay 37 6-operates in response to theflicker the following circuit is completed :earth, armature 392 and itsfront Contact, armature388 and its back contact,

armature 384' and its front contact, lead 740, lead 464, niultipledcontacts 5, 6 and 7 in the bankof wiper 502, lead'33, lead 682, frontcontact and a-rmature 182, lead 45, winding of relay 330' to battery.The operation of relay 330 asbefore eifects the stepping of thejtestswitchover the nextthree positions. In each of these positions earthover wiper501 is extendedto the indicating lamp 543. i I

When the test switch reaches its 8th position the circuit of relay 341is opened and earth is connected over wiper 501 andthe multipled 8th,9th,'10th and 11th contacts in its bank to the junction assignedindicating lamp 544. The stepping of the test switch over the 8th and9th contacts is effected by earth from the interrupter 400 beingextended over armature 329 and its back contact lead 454 to the contactsengaged by wiper 502 whence a circuit iscompleted forrelay 330 in theusual manner. While the test switchisin its'ninth position, a circuit iscompleted from earthen wiper 503 to the ninth contact in its bank, lead444, lead 745, lead'406 and wiper 626 to the assignment lead associatedwiththe junction.

nism with this flash. Uponeach operation of relay 376, earth isconnected at "armature Accordingly the junction is assignedand the I I377 to lead 434 over lead 704 whence'it is eX- tended tothellthfcontactin the bank of wiper 502 and serves to operate relay 330 asbefore, -When the test switch reaches posit1on-12, indicating lamp 545is lighted and a circuit is completed over wiper 503 and lead 448, forrelay 344 which accordingly operates.

Thereupon at armatures 348 s3 5l,it connects g wipers 525-528 of thenumber-setup switch NS by way of-leads 730-733 and 449 -452,

leads 763767. lead s' 7 982, armatures 186- 189 and 'leadsf5 8 to wipers641' 1644 of the auxiliarysecondary. distributor ASD and at armature345' completes the following cir-' cuit: earth,winding ofrelay264,armature.

267 and its back contact, armature 345 and its front contact. lead 713,lead 470, first contact in the bank of wiper 530 and said wiper, windingof magnet 531 to battery. Moreover at armature 346 it opens the homingcircuit of the numbcr-set-up switch and connects the commoning ofcontacts 216 to the pulsing lead from relay 264. Relays 264, 266 and 268now interact in the manner previously described to send impulses and theswitch NS is thus stepped round to etl'ectthe setting up of the digitstorage relays in the impulse sender, this corresponding to theoperation of the digit keys by the operator. It will be understood thatthe appropriate contacts in the banks of wipers 525 528 of thenumberset'up switch are suitably jumpered to earth so as to effect thesetting up of the test number which will secure that the test call isrouted back to the routiner in a manner which will be more fullydescribed subsequently. IVhen the switch NS reaches its 16th positionafter having set up a full 7-digit number, a circuit is completed fromearth on the 16th contact in the bank of wiper 529. lead 768, 12thcontact in the bank of wiper 504, interrupter springs 508, lead 441,lead 726, back contact and armature 313, lead 700, lead 439, magnet 50.to battery. Accordingly the magnet is energized and since the abovetraced circuit includes the interrupter contacts 508. the test switch isadvanced one step into the 13th position. In this position the circuitrelay of 344 is broken and it de-energizes, thus disconnecting thewipers of the number-set-up switch and completing circuits to cause thisto return to normal under the control of interrupter contacts 532. Inthe 13th position of the test switch indicating lamp 546 is lighted anda circuit is completed over wiper 503 and lead 456 for relay which uponoperating, at armature 356 locks to earth provided at armature 184 ofthe relay 180. Moreover at armature 354 it connects battery throughresistance 399 and relay 389 over lead 709 to the negative trunkconductor and at armature 355 connects earth through the lower windingof relay 385 over lead 719 to the positive trunk conductor.

.This corresponds to the taking of the junction line by the A operatorand causes the starting ot the sender.

The code digits set up on the storage relay groups in the impulse senderin response to the operation of the number-set-up switch are now sentout, suitably translated so as to cause the routing of the call over aspecial test level in a selector whence connection is established backto the routiner over the leads 481. 482 and 483. Vhen switching throughis effected at the selector, a circuit is completed for relay 367 whichextends as follows: battery, lower winding of relay 367, lead 7 29,normally closed springs controlled by armature 359, lead 482, negativetrunk conductor, polarized relay in the junction relay set, positivetrunk conductor, lead 483, armature 363 and its back contact, normallyclosed springs controlled by armature 358, lead 728, upper winding ofrelay 367 to earth. Relay 367 is accordingly now operated but thepolarized relay in the junction relay set does not operate at this timeowing to the current flow being in the wrong direction. Upon theoperation of relay 367, at armature 368 a circuit is prepared for relay364 and at armature 369 a circuit is completed for relay 370 and thisaccordingly operates in turn and at armature 371 prepares a circuit forrelay 309 oy er leads 702 and 703. After the junction has been assigned,a steady earth should be applied to the lamp lead and if this conditionis duly fulfilled, relay 376 will be held over its top winding. In case,however, any irregularity should have occurred so that flash or flickerpulses are still being applied to the lamp lead, relay 367 willdeenergize and will thereupon complete a circuit for relay 309 whichlooks up and gives the alarm as will be described subsequently. Relay370 also at armature 372 prepares a circuit for relay 374, while atarmature 373 relay 304 is connected over lead 734 to the test conductor481 extending from the selector level for a purpose which will bedescribed subsequently.

The sending of the numerical digits from the sender will now beinitiated and accordingly relay 367 will pulse in response thereto, oneach de-energization completing a circuit for relay 374 which owing toits slow characteristic holds up throughout the train. Thereupon atarmature 375 earth is connected over lead 432 to the 13th contact in thebank of wiper 502 and when this is removed at the end of the train ofimpulses the test switch is advanced one step in the usual manner to the14th set of contacts whereupon indicating lamp 547 is lighted. Thefurther stepping ot the test switch depends on the successful receptionof the digits and also on the test which is made by means of relay 304for guarding earth. The earth for maintaining the connection should besupplied at this time from the junction relay set and is thereforeOPEI'ZIthG to shunt relay 304. If relay 304 remains deenergized, atarmature 305 and its back contact earth is applied to the 14th, 15th and16th contacts in the bank of wiper 502 over armature 375 and accordinglythe test switch is advanced through these positions as the variousdigits are received. IVhen the test switch is advanced to its 14thposition after the reception of the first numerical digit, a circuit iscompleted from the earth on wiper 503 and over lead 460 for relay 357and this upon operating, at armatures 358 and 359 connects relay 367across the leads 482 and 483. That is to say the operation of relay 357,when the test switch is advanced to its 14th position, re-

verses the connections of relay 367 to the junction from the selectorlevel, extending over leads 482 and 483, so that in case either thenegative or positive conductor is in contact with the correspondingconductor of some other junction, this reversal will prevent relay 367from responding to impulses and the test switch will accordingly beprevented from advancing. This operation only takes place for thereception of the second numerical digit and when this has beensuccessfully completed, the test switch is stepped so that relay 357 isno longer energized. The third and fourth numerical digits are thenreceived in a similar manner and the test switch is accordingly steppedto its 17th position. In this position indicating lamp 548 is lightedand the earth on lead 427 is also extended over wiper 503 and lead 465to relay 360. The operation of relay 360 at armature 363 connects busyflash battery from lead 480 to the positive lead from the selector.Moreover at armature 361 contacts 331 of relay 330 are short-cir cuitedso as to prevent undue delay inthe operation of the alarm owing to thefact that this test is prolonged for three pulses of busy flash. Theapplication of busy. flash battery over the positive lead should resultin the repeating back ofa corresponding connection from the junctionrelay set that is to say the connection of battery to the lead cominginto the routiner over wiper 627 of the junction distributor JD Hencesince relay 352 is still locked up and therefore armature 355 isoperated, a circuitis now completed for the lower winding of relay 385."Upon the operation of relay 385, at armature 388 a circuit is completedover wiper 502 of the test switch for relay 330 and when relay 385releases, this circuit is broken and accordingly the test switch isstepped. In this manner it moves a further three steps and thus advancesinto its 20th position. A circuit is now completed for indicating lamp549 and also from earth on wiper 503, by way of the 20th contact in itsbank, lead 458,

lead 723, front contact and armature 368,

lead 723, and winding of relay 357 to battery. The operation of relay357 as before reverses the connection of windings of relay 367. Theoperation of the polarized relay by connecting battery to the negativelead eifect's the operation of relay 385 and this as before operatesarmature 388 though in this case earth is extended over lead 739, lead463 to the 20th contact in the bank of wiper 504 and thence over theinterrupter contacts 508, lead 441, back contact and armature 313, lead700, lead 439,-winding of magnet 507 to battery. Accordingly magnet'507operates and breaks its own circuit at contacts 508 and thus advancesthe wipers of the test switch into the 21st position whereuponindicating lamp 550 lights. The earth on wiper 503 is now extended overlead 459, winding of relay 364, lead 723,-front contact and armature368, lead 722, winding of relay 357 to battery whereupon relay 364operates and relay 357 is maintained operated. At armature 366 relay 364connects ringing current from the interrupted generator over theinduction coil I to the positive lead 483 whence it is extended over theselectors used and through the condenser'in the talking circuit to thecorresponding contact in the bank of wiper 628 of the junctiondistributor JD lead 405,

windingof alternating current relay 393 to earth. If the talkingcondenser is in proper condition, the ringing current thus trans mittedis sufficient to cause the operation of relay 393 and this relaycompletes a circuit as follows: earth, front contact of armature 327,armature 394 and its front contact, lead 477, lead 752, 21st contact inthe bank of wiper 502 and thence to operate relay 330 as before, so thatthe test switch is advanced to its 22nd position. Indicating lamp 551now lights and relays 357 and 364 are de-energized and accordingly thecurrent is reversed to its original-direction over the junction lineandthe ringing lead and the alternating current relay 393 are disconnected.Upon therestoration of the current flow to normal, the polarized relayin the junction relay set revleases and disconnects the battery feedthereupon releasing relay 385. The following circuit is now completed:earth, armature 392 and its front contact, armature 388 and itsbackcontact, lead 741, lead 445, 22nd con tact in the bank of wiper 504and said wiper, interrupter springs 508, lead 441, lead 726 back contactand armature 313, lead 700,1ead 439, winding of magnet 507 to battery.Accordingly the test switch is advanced to its 23rd position, in whichposition the earth on wiper 503 is extended over lead 457 toshortcircuit relay 352 and this after a slight interval releases and atarmature 354 disconnects the battery feed through relay 389. Since theline relay of the junction relay set is in series with relay 389, itwill also restore at this time and open the junction lamp circuit sothat relay 376 should also now restore. Moreover the earth'on wiper 501is now extended to the indicating lamp 541 to indicate the particulartest in progress. When the test switch steps to its 24th position sincethe last two contacts in the bank of the homing wiper 506 arepermanently connected to earth, it now returns to its normal positionand relay 127 is again operated. The test switchis now operated in themanner previously described and earth through the interrupter 485 isconnected over lead 453 to the first two contacts in the bank of wiper502. Consequently testing for a free junction now recommences in themanner previously described and when such a junction is found the testsare carried out on it in the same way. \Vhen all the junctionsaccessible over the junction distributor JD have been either tested orfound busy, the junction distributor J D is brought into use and testsare made on the junctions accessible from its bank. lVhen these have allbeen dealt with, another idle position is seized and the junctionsassociated therewith are routined.

In order that an indication may be obtained at any time of the number ofpositions which have actually been routined, the bank of switches suchas SD over which wiper 612 passes is multipled to the bank of a routineindicating switch RIS as shown in Figs. 5 and 7. The routine indicatingswitch is stepped round, under the control of the routine indicating keyRIK, the operating circuit for stepping magnet 516 being traced asfollows: from battery, winding of stepping magnet 516, lead 95, contactsof routine indicating key, lead 96, armature 291 and its front contact,to earth, armature 291 being operated when the routine finish relay 285is operated. Hence if the particular positions connected with in anyposition of the switch RIS have been routined, the associated indicatinglamps will be lighted, and thus an indication will be given of theprogress of the test. Alternatively, instead of the switch RIS it wouldbe possible to make use of six relays each carrying ten pairs of springsand adapted to make connections similar to those effected by the switchRIS. This arrangement would have the advantage that on the ressing ofthe key corresponding to the key IK, all the lamps would be lighted atonce.

The release alarm key RA is provided in order to enable the alarm to bedisconnected after afault has been found. It will be seen that earth isprovided over the normall closed contacts of this key and leads 690 and72 to lock up the alarm relay 309 which is operated as shortly to bedescribed when a fault is found.

The restart key RS enables the testing operation to be re-started afterit has been stopped due to the distributors making a complete revolutionwithout finding an pos tions idle and untested. At the left-hand springsof this key earth is then removed from lead 34 so as to open the lockingcircuit of the routine finished relay 285 while at the right-handsprings a point in the locking circurt of relay 152 is opened;consequentlv cond tlons are again restored for enabling the distributorsto make a further test for positions which are idle and have not yetbeen dealt with.

It may be desirable in some cases to perform a continuous routine testupon a certam position or also upon a certain trunk particularly in caseafault has originally been encountered and it is now desired to see thatit has been properly cleared. For

a continuous routine test of a particular position, the key PCR isoperated before the start key SK and the former at its left-hand springscompletes a circuit for relay 119 which operates and performs thefunctions previously described. At the right-hand springs of the keyPCB, a circuit is completed from earth, armature 117 and its backcontact. back contact and armature 156, right-hand springs of key PCR,winding of relay 137 to battery. Upon operating, relay 137 at armature139 connects earth to the stepping keys, at armature 1 10 opens a pointin the homing circuit of the secondary distributors, at arma ture 141prepares a circuit for relay 285 and at armature 142 completes a lockingcircuit for itself. The group stepping key GS is now operated to movethe primary distributor wipers into engagement with the requiredsecondary distributor, the circuit extending from earth, front contactand armature 139, springs of key GS, lead 67:2. lead 68, lead 168,winding of magnet 607 to battery over lead 29 to the winding of relay233. Then the position stepping key PS is operated and each time itscontacts close a circuit is completed from earth at armature 139,contacts of key PS, lead 666, lead 27, wiper 605 to magnet 610 andthence to battery through relay 233 as before. \Vhen the requiredposition has been connected with as indicated by the lighting of thecorresponding lamp, the start key is thrown and upon the operation ofthe start relay 115, the circuit of relay 131 is completed at armature116 and at armature 118 a circuit (which will not become effective inthis case) is prepared for stepping the secondary distributor. Upon theoperation of relay 131, the test proceeds in the manner previouslydescribed on the particular position sc- I lected. When all thejunctions accessible over the first junction distributor have beenroutincd, relays 172 and 175 are operated as previously described andrelay 175 serves to transfer the stepping circuit to the second junctiondistributor and locks up over its own armature 178. Vhen all thejunctions accessible from the bank of the second junction distributorhave been tested, relay 166 is operated as before and opens the circuitof relay 175 at armature 169. \Vhile relay 175 holds up. however, acircuit is completed from earth, armature 179 and its front contact,lead 674, front contact and armature 1'70, armature 141 and its frontcontact, lead 64, back contact and armature 2S8. upper winding of relay285 to battery. Relay 285 being of the two-step type operates its lightarmature 290 at this time, thereby shortcircuiting its lower windingover lead 31 and the lefthand contacts of the re-start key. when relay1'75 releases after its slow period the circuit of the unctiondistributor magnet is opened and it accordingly steps the associatedwipers thereby opening the circuit of relay 166 which also releasesafter a slight interval. Moreover at armature 170 the shunt earth isremoved from the lower winding of relay 285 and it now operates fullythereby lighting the routine finished lamp and performing the otherfunctions previously described. If it is desired to make a furtherteston the junctions in this position, the re-start key is operatedwhereupon at the left-hand contacts of this key the looking circuit ofrelay 285 is opened and the previous conditions are restored.

In case it is desired to make a continuous routine test on a particulartrunk, the key TOR is operated instead of the key PCR. Thereupon at theleft-hand contacts of this key a circuit is completed for relay 119 asbefore, while at the right-hand contacts earth from the back contact ofarmature 117 is extended to the winding of relay 162. Relay 162 uponoperating, at armature 163 opens the pulsing circuit for the junctiondistributor so that this shall not be advanced at the end of each test,at armature 164 applies earth to the stepping keys and at armature 165completes a lockin circuit for itself. 'In addition to the keys S andPS, it will be necessary inthis case to operate also the key TS whichcompletesa circuit which is readily traceable for the magnet of theproper junction distributor. This test will continue on the trunkselected untilthe start key or the key TCR is restored.

In order to facilitate the location of faults, the key FL is providedand when this is operated acircuit is completed for relay 119 as beforeand also relay 143 is operated. This at armature 144 supplies earth tothe stepping keys in the usual manner and opens the circuit of thevisible alarms, at armature 145 opens a point in the circuit of relay131, at armature 146 prepares a circuit for relay 180, at armature 147completes a locking circuit for itself, at armature 148 prepares astepping circuit for the auxiliary secondary distributor since as relay131 will not be operated in this case no circuit is completed by it, atarmatures 149 and 150 prepares connections over the auxiliary secondarydistributor to the order wires extending to the position in question andat armature 151 removes earth from the second group ofmultipled-contacts in the bank of wiper 606 of the test switch. Sincerelay 180 is not yet operated in this case, this means that tests willstart at position 13 of the test switch owing to the homing earthremaining connected to the first group of multipled contacts. Theattendant may now if he Wishes by operating the appropriate steppingkeys set the distributing switches on to any desired junction at anyposition and theifoperate the start key and observe from the supervisorylamps the progress of each test. When the test switch has rotated toposition 13, relay .180 is operated over Wiper 505 and the test thenproceeds in the normal manner. It will be noted that when the attendantis locating faults, since relay 131 does not have to be operated, he maymake connection with a position which is staffed, and may if he wishesinsert the jack J in the plug P and order up a connection from theoperator overa particular junction. It will be seen that when the jackis inserted in the plug, .the transmitter and receiver of a handset 89specially provided onthe routine are connected up to leads 76 and 77 andthence through the repeating coil windings to the upper and lowerwindings of the relay 395. This relay accordingly operates and atarmature 39.6 connects up the other windings of the repeating coil in acircuit includingarmatures 149 and. 150, 192 and 193 and leads 9 and 10to wipers 639 and 640 of the auxiliary secondary distributor ASD.Moreover, at armature 397 a point is opened in the auxiliary circuit forrelay 180 andat armature 398 a circuit is completed for advancing thetest switch to. its thirteenth position. The attendant will thenremovethe jack J thus file-energizing relay 395, which at armature 397permits relay 180 to operate to be made on all the common apparatus onlyfour junctions at the position need be tested;

Moreover, as previously pointed out, with the arrangement shown thecapacity of the two junction distributors is 46 junctions and it is notdesirable to provide more than two of these distributors. should be 50junctions incoming to the position, the remaining four can convenientlybe dealt with over contacts 1,:'4 of the firstjunction distributor, thechangeover from junc tions 14to junctions 4750 being made by suitablerelays. In the present instance the positions are assumed to be equippedwith 50 junctions and accordingly the quick routine test is madeoverjunctions 47/50. For this purpose the quick routine key QR is thrown,whereupon atthe right-hand contacts of this key a circuit is preparedfor relay 159. Moreover, at the left-hand springs ofthe key QR, earthis'extended over lead 687, lead 70, winding of relay 299, lead 71,armature 194 and its front contact, lead 4, wiper 645, lead 409, windingofrelay 536 and winding of relay 535-tobattery. The relays 535 and 536it will be understood are associated with the particular position andmay conveniently be mounted In case, however, there adjacent to thebattery feed relay 533: relay 299, however is located in the routinerand serves for all the positions. Upon the operation of relays and 536the leads from the first "four contacts in the banks of wipers 625-4528are transferred to the lamp, assignment and positive and negativeconductors of junctions 47 50. Moreover at armatures 300303 of relay 299the indicating lamp leads from the first four contacts in the banks ofall the distributors J D are transferred so to connect up the indicatinglamps connected with junctions 1T50 instead of those associated withjunctions 14. The test now proceeds in the usual way upon the operationof the start key and when junctions l750 have been routined a circuit iscompleted over wiper ($29 in 5th position, lead 83, lead 662, right-handcontacts of key QR,lower winding of relay 159 to battery. Belay 159 uponoperating, at armature 161 looks up over its upper winding and atarmature 160 brings down relay 131. The junction distributors are thenmoved to the position routined contacts, that is, the 24th position ofthe second junction distributor, and the operation of relay 166 bringsdown relays 152 and 159 and allows testing to take place for the nextfree position on which the quick routine test is made in similar manner.Hence it is possible by this means to make a quick routine test whichwill test all the common equipment at the operators position and alsojunctions 17-50 and will only occupy a fraction of the time required forthe full test. It will be appreciated that in the case of positionsequipped with 50 junctions, in order to test all the junctions it willfirst be necessary to make the full routine test which will deal withjunctions 146 and subsequently to make the quick routine test which willthen deal with junctions 4750.

The arrangements for giving an alarm may now be briefly dealt with. Itwill be appreciated that the advance of the test switch to initiate atest is dependent on the success of the previous test and that if thetest switch remains in any position except its normal one for more thana predetermined interval, the alarm will be given. A circuit may becompleted for the lower winding of the alarm relay 309 over armature 377in case the junction lamp does not receive full earth, as previouslymentioned but in general relay 309 will be operated after a timeinterval under the control of relays 306 and 314. When relay 314 isoperated, at armature 317 it connects an additional earth to the motorstart lead 490 and at armature 315 connects up interrupter 316 to relay306 and at armature 320 prepares a locking circuit for this relay. Relay306 first operates its light armature 308 and subsequently also armature307 thereby transferring the pulses to relay 309. If the conditionspersist, relay 309 operates in due course locks up to the key RA at armatnre 312, at armature 313 opens the circuit of magnet 507 to prevent thetest switch moving, at armature 311 lights an alarm lamp, and atarmature 310 connects up an alarm bcll, assuming relay 143 is notoperated. It will be seen that the circuit prepared for the lowerwinding of relay 311 at armature 183 is opened by relay 330 each timethat relay operates to step the test switch. The normally energizedrelays 278 and 280 associated respectively with the junctiondistributors and the primary and secondary distributors serve tosupervise the operation of the magnets of these switches. In the case ofthe primary and secondary distributors, battery feed is through relay233 and this at armature 231 connects earth to lead 58 and hence throughlamp 283 to relay 314. Similarly battery feed relay 295 at armature 296supplies earth through lamp 2t lVhen the start key is restored, earth isconnected over armature 123 to lead 57 and should relays 278 and 280 notoperate in due course, relay 314 would again be operated and the alarmbe given so that supervision is obtained of the return of the switchesto normal. The routine finished lamp 528% also obtains its battery fromrelay 311 so that an alarm is given in case the attendant does not atonce notice the lighting of the lamp.

It will be understood that armatures 196-- 204: of relay 195 and 200213of relay 205 are wired to the auxiliary secondary distributors ASD andASI) in the same way as the corresponding armatures of relay 185 arewired to the auxiliary secondary distributor ASD.

\Vhat I claim as new and desire to secure by Letters Patent is 1. In atelephone system, automatic routine testing equipment for testingtelephone apparatus, a hunting switch for associating said testingequipment with said telephone apparatus, means for testing idle ones ofsaid apparatus in turn until all have been tested, and means responsiveto the completion of a test on said one of said apparatus and theassociation of a special potential therewith for preventing the seizureof said apparatus again by said hunting switch.

2. In a telephone system, automatic routine testing equipment fortesting telephone apparatus, a hunting switch for associating saidtesting equipment with said telephone apparatus over the bank contactsof said switch. means for advancing said hunting switch to test saidbank contacts to find one associated with a piece of apparatus incondition to be tested, means for routine testing said piece ofapparatus, and means for stopping said routine testing operation when nocontact is tound associated with a piece of apparatus not in conditionto be tested.

3. In a telephone system, automatic routine testing equipment fortesting telephone

